The invention is based on a pressure regulating apparatus as defined hereinafter. In a pressure regulating device, a sealing groove machined into the valve housing and into which an elastic seal is placed has already been proposed. To make this groove, the additional step of making a plunge cut is necessary, and the sealing ring has to be stretched in order to introduce it into the sealing groove. This application is an improvement over U.S. Pat. No. 4,679,537 and other pending applications all of which are owned by the assignee of this invention.